Sound Source Localization by Asymmetrically Arrayed 2ch Microphones on a Sphere

In this paper, we propose a novel system to localize a sound source in any 2D directions using only two microphones. In our system, the two microphones are asymmetrically placed on a sphere, thus, (1) the diffraction by the sphere and the asymmetrical arrangement of the microphones yield the localization cue including the front-back judgment, and (2) unlike the dummy head system, no previous measurements are necessary due to the analytical representation of the sphere diffraction. To deal with reverberation or ambient noises, we consider the maximum likelihood estimation of the direction of arrival with a diffused noise model on a sphere. We present a real system that we built through the investigation of the optimal microphone arrangement for speech, and give experimental results in real environment.